Sodiated Nafion membranes for sodium metal aprotic batteries

The expansion of the use of renewable energy sources replies on the availability soon of cheap, safe and suitable energy storage systems. In this respect batteries can be a pivotal solution. Among the available battery chemistries, lithium-ion batteries (LIBs) are currently the state-of-the-art coupling excellent performance, minimal self-discharge, and technological readiness. However, costs and sustainability together with safety are hindering the booming of LIBs. Aprotic sodium ion and sodium metal batteries are similar technological options with more balanced figures in terms of performance/sustainability compared to LIBs. Focusing on safety, for both LIBs and NIBs hazards are originated by liquid electrolytes that are flammable, volatile and contain fluorinated salts. Thus, technological improvements on the electrolyte side are the key also for the commercial exploitation of NIBs. Here we propose and demonstrate for the first time in the literature the use of a sodiated Nafion membrane as a single-ion conductor electrolyte for sodium-ion batteries.